Application/vnd.nok-ringtone, image/vnd.nok-oplogo and image/vnd.nok-picturemessage have been defined in Smart Messaging Specification 3.0, available at http://www.forum.nokia.com/main/1,35452,1_2_5_3,00.html.
Image/vnd.nok-3dscreensaver is a MIME type for 3D screensavers at the moment supported in 3410. More info and tools from http://www.forum.nokia.com/mesforum/main/1,35452,1_75_28,00.html.
Image/vnd.nok-wallpaper is a content type for wallpapers which cannot be send or forwarded from the phone. File format can be jpg, gif or png.
"Nokia Messaging Characteristics" -document tells which terminal supports these content types, http://www.forum.nokia.com/main/1,35452,1_2_7_1,00.html -> Technical.